Breaking Down the March Tornado Outbreak

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New images from the nation's Storm Prediction Center show how
much of the South and Midwest were affected by the severe weather
and tornadoes on Friday (March 2).

An entire
month's worth of tornadoes struck across parts of the
country from March 2 into the morning of March 3. The Storm
Prediction Center received 81 reports of tornadoes on March 2,
according to data filtered to remove duplicate reports of
tornadoes. For the entire month of March, the 10-year average
number of tornadoes is 87, according to the Weather Channel's
severe weather expert Greg Forbes. The National Weather
Service's storm survey teams have not yet confirmed the tornado
reports, so these numbers could change. But if the numbers hold,
the outbreak could go down as the largest single-day outbreak in
March history.

In 2006, the biggest March outbreak saw 105 tornadoes from March
9 to 13. March 12 of that outbreak saw 62 confirmed tornadoes.
Yesterday's outbreak could top that total.

The National Oceanic and Atmospheric Administration created a map
of areas with high rotational velocity — an important ingredient
for forming tornadoes — using data from NOAA's network of NEXRAD
radar installations, processed by the National Severe Storms
Laboratory in Norman, Okla. By examining these images,
forecasters can determine the approximate tracks of so-called
supercells, which feature strong rotation and are known for
producing tornadoes. Some of these supercells had rotational
velocity up to 180 mph (290 kph), and so their signature stands
out from the surrounding storm areas. Features such as these are
watched carefully for possible tornado outbreaks.

To see how the March 2 outbreak compared with the April 27, 2011,
outbreak — the
largest tornado outbreak in recorded history — meteorologists
at the Storm Prediction Center compared the tornado and severe
weather warnings issued during those outbreaks (image below). On
the March 2 outbreak, the area of warning covered nearly 500,000
square miles (1.3 million square kilometers). During the April 27
outbreak, the area of warning covered more than 1 million square
miles (2.6 million square km).

An from NOAA's Suomi NPP VIIRS instrument shows the overshooting
cloud tops and intense storms associated with March 2 tornado
outbreak. The imagery was acquired over Illinois, Indiana, Ohio
and Kentucky. Polar-orbiting satellites track the subtle changes
in the environment that can trigger potentially deadly weather
conditions, from tornadoes to tropical storms. Current
operational POES data was critical for issuing watches and
advisories days in advance of this outbreak.

You can follow OurAmazingPlanet staff writer Brett Israel on
Twitter: @btisrael.Follow
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